In Mass Effect 2, Liara is on the planet lllium, she can not be recruited as a squad member, but will request that Shepard perform a few tasks for her. Also she is involved in the Lair of the Shadow Broker DLC, and is involved in a few things Behind the Scenes during Shepard's disappearance, which can be seen in the ME2 comic.
She is, but you cannot recruit her.
It's Liara's assistant (the girl that sits outside the door
Bioware Heavily Implies Liara Should Be Your Canon Romance
After beating the Citadel, go to the Artemis Tau cluster to look for Liara T'soni, and you'll get her.
That's a negative. You may play the Shadow Broker DLC anytime after you have reached Illium. Liara will be in her office, just go and talk to her about it.
You have to take Liara (the asari on your team), with you on every mission. You have to do all the side missions to get the achievement, not just the main missions.
Not unless you load an early save file. You need those key missions so you can interact with her after you finish those.
If he died in Mass Effect 1 then he is not in Mass Effect 2. If he survived Mass Effect 1 he shows up in Mass Effect 2 but he can not be killed.
Do the missions that say "recruit the (insert class type)"
Mass Effect 2 is a 15.
If you pursued and completed a romance with her in Mass Effect 2 there will be some conclusion. Yvonne Strahovski has been cast for Mass Effect 3 but not as squadmate. Miranda's role will probably be larger than Ash's Mass effect cameo appearence. Project director Casey Hudson said in an interview that he hopes she's okay. Miranda and Shepherd will have a romantic conclusion based on everything the Mass Effect team at Bioware has realeased. But you will not be able to start a romance with her in Mass effect 3. If you want to romance her do it Mass Effect. There will be a love triangle situation between Shepherd, Miranda, and Ashley or Liara.
No, Mass Effect 2 has a completely different weapon system.